1. Fields of the Invention
The invention belongs to the fields of radio electronics, communications, information technology, television, interactive television, industrial and medical television, videophone and videoconferencing.
2. Art of the Invention
Interactive television features an operation sequence designed to form a video image corresponding to expectations of the users. The interactive television combines the following operations:                a) video signal preconditioning and formation,        b) transmission of the video signals,        c) conversion of the video signals,        d) video imaging by means of display components,        e) formation of interrogation signals for the data formation, conversion and/or display components.        
Eye foveal properties are used for reducing an excessive video image by way of reduction of the spatial, color resolution characteristic of the video image or its parts, as well as by using the resolution characteristic versus the time of displaying the image to the user according to the function of his eye resolution.
The eye faculties are widely studied in medicine and are described as the function of the eye resolution threshold. They are used for the diagnostics of eye and the entire body diseases. Development of sensor technique level and identification of the eye dynamic characteristics for the time being in IPC A61B 3/14 class is represented by a variety of devices and methods for determining: coordinates and orientation of the user's eye, their accommodation, eye apple diameter and eye winking factor (invention of the USSR No. 145303, 1960, the U.S. Pat. Nos. 3,507,988, 1970, 4,397,531, 4,720,189, 4,729,652, 4,946,271, 4,973,149, 5,430,505, 5,583,795, 5,649,061), which are used for a while only in aviation and in the military technology.
Eye dynamic characteristics comprise coordinates and directions of eye optic axes, accommodation, convergence, eye apple diameter and other characteristics. The eye static characteristics comprise long-time characteristics associated with eye individual features (shortsightedness, astigmatism, daltonism, etc.) and affecting the function of the eye spatial, time and color resolution threshold versus the azimuth and elevation angles with respect to the eye optic axes.
Analogues describe proposals for using spatial resolution dependences of the azimuth and elevation angles of video image area relative to the eye optical axis in the facilities of the formation, conversion and transmission of video signals, as well as in the information display facilities.
Thus, patent of the U.S. Pat. No. 4,028,725 “High-resolution vision system” proposes the facility, which consists of the facilities of video signal formation presented as sensitive-to-image sensors (TV cameras) and information display facility presented as a display mounted on the user's head. This facility uses eye faculty, which reduces spatial resolution of the video image formed on the screen of the users' video display facility from the line of vision to the sight periphery. This function is realized by the facilities of video signal formation consisting of two TV cameras with a wide and a narrow fields of vision. Video signals of high and low spatial resolution are formed in a TV camera with a double concentric field of vision. Video signals are transmitted via data channels to the video display facility provided with two cathode-ray tubes, which jointly with the optical system generate the video image: wide—with low resolution and narrow images—with high resolution. An optical servo-operated mechanism coalesces these two images and dynamically co-locates the image center of high resolution with the optical axis of the user's eye. The optical servo-operated mechanism contains an optical sensor, using for determining the dynamic sense of the user's eye optical axis and generating control signals coding the sense of the eye optical axis. The above signals are fed via the data channel to the TV cameras, which according to the interrogation signal modify the orientation of the optical axis of the TV camera of high resolution. In such a way, the user's eye always looks at image of high resolution in the display screen. The device allows using a binocular mode. It also allows using a computer inputs connected to the display or from, sensors or using videotape. This solution permits to process the image presented for one user.
U.S. Pat. No. 4,348,186 “Pilot helmet mounted CIG display with eye coupled area of interest” is interesting by the fact, that it measures the user's head and eye position using head-mounted facilities of formation of high resolution video image, makes a projection of the sector of high resolution video image to cockpit canopy and reflects its motion. The proposed facility fits only for individual usage, because it operates determining one eye area of interest. In the simulator, proposed by the American authors, it is offered to form video image sectors as a series of concentric rings of different ranking such as to present more in detail sectors of central rings, than periphery rings, i.e. with radial reduction of the spatial resolution.
U.S. Pat. No. 4,479,784 “Momentary visual image apparatus” further develops the ideas of U.S. Pat. No. 4,348,186. The above technical solution differs in that the coordinates of the line of eye vision are used for the dynamic determination of the foveal field size of the eye high resolution, with the creation and shift of this area of video image sectors with high quality level on the screen, which occurs faster than saccadic eye movements. It is also proposed to synchronize facilities of image display of low resolution with facilities of projection of high-resolution image by the azimuth and elevation angles. According to one of the proposed variants it is proposed to mount the eye position sensor on the helmet.
In this patent it is proposed to provide an electronic fusion of the image sectors of two resolutions. The difference between the facility and the system consists in the fact that the boundaries of the image sectors are not subject to the dynamic adjustment, but only may be shifted from one vision point to another vision point with a high speed. The size of sectors is assigned by the projection facilities of high-resolution images to place the projection of the foveal area into the image of high resolution, whereas the facilities of low resolution generate the image, which surrounds the above image of high resolution.
The distinctive feature of the above invention consists in the availability of only two sectors with different resolution. At that, the boundaries of the sectors do not modify the form, and every sector features permanent resolution.
U.S. Pat. No. 4,634,384 “Head and/or eye tracked optically blended display system” describes the design of the display generating an image with the resolution corresponding to the spatial position of foveal area of the observer's eye.
The above system and the U.S. Pat. No. 5,808,589 “Optical system for a head-mounted display combining high and low resolution images” has only two areas. The boundaries of these areas are constant respectively, the field of its application is very narrow—flight simulators with dome-shaped screens.
U.S. Pat. No. 5,808,589 and other similar devices helmet-mounted information display facilities, where the image is formed for each eye separately. The sectors of low- and high-resolution images are combined in a device by using a single a facility. The above device is provided with two displays: with high and low resolution, accordingly, and the optical system, generating the single image consisting of the sectors with different resolution and permanent boundary between them. The proposed boundary should correspond to the projection boundary of the foveal field of the eye retina to the screen.
U.S. Pat. No. 5,980,044 “Area of interest display system with image combining using error dithering” developing U.S. Pat. No. 5,326,266 provides a two-display system of low and high resolution, as well as the facilities of their combination, in particular, the methods of combining two images. In this connection, it is proposed to take into account the current position of the user's eyes.
U.S. Pat. No. 4,513,317 “Retinally stabilized differential resolution television display” proposes to use eye foveal faculty in the TV-display creating two zones in the screen: with high and low resolution in image sector raster scanning. The facility is furnished with a special video camera generating two sectors of high and low-resolution image with their mutual positioning depending on the eye position. In this connection, the best ray of the cathode-ray tube determines the high resolution capacity and vice versa, the worst ray of the cathode-ray tube determines the lowest resolution.
The disadvantage of this method consists in the impossibility of its use for long distances and/or for several users simultaneously.
Eye foveal faculty is also used for the reduction of the bandwidth of the video information channel, for example in the U.S. Pat. No. 4,405,943 “Low bandwidth closed loop imagery control and communication system for remotely piloted vehicle”. The system is designed for the reduction of the bandwidth in the “closed video line” and the communication system for the control of a remotely flight vehicle.
The devices consists of two parts:                a remote part comprising a digital camera, video memory, receiver and video memory reader with different resolution; and        a local part comprising facilities for interrogation signal generation and facility of the above data transmission to the unpiloted flight vehicle.        
All these facilities and methods are characterized by the individual nature of their use in aircraft simulators, systems of industrial or military purpose. Absolute majority of the considered technical concepts are designed for the service of one eye of the user, in rare cases—two eyes of one user. Anyway, the application a priori presumes, that the distance from the source of video information to the user will be minimized. It is restricted by the period of the data signal transmission via the data channels from the user to the source of video information and vice versa. It should be smaller than the period of the eye optical axis shift from one pixel to the other pixel of the video frame perceived by the user. Otherwise, video image defects will be observed at the boundary of the video image sectors at the turn of the user's eye optical axis. An on-line communication line should be organized for the transmission of interrogation signals coming from the information display facility to the source of video information.
To prevent the degradation of visual perception of video image because of spotting the boundary effects with the user's eye, some patents, e.g., U.S. Pat. No. 5,071,209 “Variable resolution nonlinear projection system” proposes to abandon distinct boundaries of video image, and instead of this to create the image with gradually variable pixels, the size of each of which corresponds to the dependence function of the eye resolution. In case of the fast eye movement any defects at the boundary between sectors of different quality level of the image will be smeared on a wide surface and will not be perceived with the user's eye or easily removed.
For using eye foveal faculties of a group of users, U.S. Pat. No. 4,859,050 1989 described the “Method and system for formation of a visual presentation and looking viewers”. According to this method a video film is shot in advance and is recorded on high-quality equipment for its further presentation on the TV-screen. There is a man in front of the screen, who watches the performance. A sensor controls the man eyes which determine the coordinates of the eye optical axis crossing with the screen. A computer converts the sensor data, calculates the objects presented on the screen at the given instance, which the viewer watches, and presents the image of these objects of the screen looking at by the viewer on the graphics. Further using the second graphics video cameras and optical device add signals of the original performance and graphics. The output signal from the video camera is recorded to a second tape of the second video recorder of standard quality. Insignificant elements of the image in the expert opinion are removed from the second tape. The above method allows using averaged grouped foveal eye faculties. However, it insufficiently reflects individual faculties of an individual user. The proposed method has a feature, which makes it unfitted for interactive television, i.e. the absence of dynamism.
Russian Federation patent No. 2134053 “Method of video information presentation and facility for its performance” describes formation of signals coding boundaries of the image sectors and quality level within each sector based on the coordinate data and user's eye orientation, the signals are supplied to the information display facility in information formation facility with conversion of the initial video signal and management of video image such, that the ecological restrictions on the creation of video image are being reduced. This invention takes into account eye foveal faculties and forms video image in the information display facility. This invention allows using eye foveal faculties of an individual user and a group of users gathered in front of one screen of the information display facility.
The above methods and devices do not allow generating, transforming or displaying video information taking into account individual peculiarities of the user's eye and individual peculiarities of a group of users' eyes.